Experimental and analytical investigations have been conducted to determine the individual and combined effects of temperature and absorbed moisture on the time-dependent mechanical response of unidirectional and cross- plied graphite-epoxy composite. Tensile creep response was measured at room temperature and four elevated temperatures (up to the glass transition region of the materials) for dry specimens and for specimens moisture-saturated at 75% and 95% relative humidity. Results were obtained for two material systems: Narmco T300-5208 and Hercules AS/3502. The stress levels used were demonstrated to be within the range of linear viscoelastic response. Superposition techniques were used to determine compliance master curves from the results for individual temperature and moisture condition, and quasi-elastic conversion was employed to extract relaxation modules behavior. Expansional strains due to temperature and moisture were measured. From measured principal properties, laminate response was predicted using time-stepped elastic analyses for the environments considered. Analytical procedures for transient and nonuniform temperature and moisture conditions were formulated. An analytical method for minimizing residual stresses during cure was developed, and sample results for the present materials are presented. Observations and recommended resulting from these investigations are included in this final report.